Update serialization.md (#1463)

* Update serialization.md

Change `denormalize` method example in 'Decorating a Serializer and Adding Extra Data' part to match with the signature of `DenormalizerInterface`

* Update core/serialization.md

Co-authored-by: Vincent <vincentchalamon@protonmail.com>

Author: guillemfondin

core/serialization.md

@@ -958,9 +958,9 @@ final class ApiNormalizer implements NormalizerInterface, DenormalizerInterface,
         return $this->decorated->supportsDenormalization($data, $type, $format);
     }
 
-    public function denormalize($data, $class, $format = null, array $context = [])
+    public function denormalize($data, string $type, string $format = null, array $context = [])
     {
-        return $this->decorated->denormalize($data, $class, $format, $context);
+        return $this->decorated->denormalize($data, $type, $format, $context);
     }
 
     public function setSerializer(SerializerInterface $serializer)